Journal of the American Chemical Society p. 1299 - 1308 (1991)
Update date:2022-08-02
Topics:
Bonner, Mary Pat
Thornton, Edward R.
A new, conformationally rigid camphor-derived N-propionyloxazolidinone effects asymmetric stereochemical control in syn-selective aldol condensations of the derived lithium and titanium(IV) enolates with a variety of aldehydes. Simple and diastereofacial selectivities of the reaction are high, and diastereomeric purities of the crude aldol adducts can be improved, usually by a single recrystallization, to levels of 98-99% in most cases. The observed facial selectivity is best explained by a transition structure in which intramolecular chelation between the oxazolidinone carbonyl oxygen and the metal induces an enolate π-facial differentiation; the major products observed are those expected from chelation control. Hydrolysis of the exocyclic carbonyl of the aldol adducts led to β-hydroxy-α-methylcarboxylic acids, with recovery of the chiral auxiliary. Consonant double-asymmetric induction with (R)-2-(benzyloxy)propanal gave the product expected from oxazolidinone chelation but nonchelation of the aldehyde benzyloxy group.
View MoreNanJing Rate Biochemicals CO., LTD
Contact:+86-25-84931986
Address:NO. 1 Hongjing Road,Jiangning Science Park,Nanjing,China
website:http://www.weichichem.com
Contact:+8613912949432
Address:Fine Chemical Industrial Base,Wujiang town,He County,Anhui China.
Shangdong Shinning Pharm co.ltd
Contact:18866891188
Address:Taishan Road, Ningyang Economic Development Zone, Tai'an, Shandong
ALPHA PHARMACEUTICAL CO,LTD JIANGSU
Contact:+86-527-84829968,+86-527-84829998
Address:suqian city
Shanghai Yuking Water Soluble Material Tech Co., Ltd
Contact:86-21-68286299
Address:4F, 13B, No. 600, South Xinyuan Road 201306, Shanghai, China
Doi:10.1021/jo01086a024
(1959)Doi:10.1246/cl.2001.382
(2001)Doi:10.1021/ja01492a047
(1960)Doi:10.1016/0040-4020(94)00913-F
(1995)Doi:10.1021/ja01630a034
(1954)Doi:10.1021/jm9608063
(1997)